1. Field of the Invention
The present invention relates generally to systems for separating selected articles from a stream of articles, and more particularly, but not by way of limitation, to a system particularly suited for sorting plastic bottles by color and by material.
2. Description of the Prior Art
A number of different sorting systems have been proposed in the prior art for sorting various articles based upon the color the articles or the characteristics of the reflected or transmitted electromagnetic radiation to which the article is exposed. Such systems have been utilized for sorting glass, plastic, fruit and other edible items, and the like.
A number of arrangements have been provided for carrying the articles through an inspection zone, and for exposing the articles to electromagnetic radiation and then collecting and analyzing the reflected and/or transmitted radiation.
For example, U.S. Pat. No. 4,131,540 to Husome et al. discloses a color sorting system wherein light is reflected off of tomatoes and the reflected light is collected and analyzed as the tomatoes fly through an inspection zone.
U.S. Pat. No. 4,657,144 to Martin et al. discloses a system for removing foreign material from a stream of particulate matter such as tobacco as it cascades through an inspection zone.
U.S. Pat. No. 4,919,534 to Reed, discloses a system for determining the color of glass bottles, wherein the light energy is transmitted through the glass bottles.
U.S. Pat. No. 5,085,325 to Jones et al. discloses a system of a very common type wherein articles are examined as they are supported upon a moving conveyor belt.
U.S. Pat. No. 5,297,667 to Hoffman et al. discloses a system of utilizing two light sources and a camera to analyze articles as they fly through an inspection zone.
U.S. Pat. No. 5,314,072 to Frankel et al. discloses a system which analyzes the transmissive characteristics of articles which are exposed to x-ray fluorescence.
U.S. Pat. No. 5,318,172 to Kenny et al. discloses a system which distinguishes different types of plastic materials based upon their reflected electromagnetic radiation.
U.S. Pat. No. 5,333,739 to Stelte discloses another system which transmits light through articles, namely glass articles, and analyzes the transmitted light to determine color.
U.S. Pat. No. 5,443,164 to Walsh et al. discloses a plastic container sorting system which utilizes both transmitted electromagnetic energy and reflected electromagnetic energy to analyze and identify articles.
U.S. Pat. No. 5,675,416 to Campbell et al. discloses an apparatus which looks at the transmissive properties of articles to separate them based upon the material of the article.
U.S. Pat. No. 5,848,706 to Harris discloses a sorting apparatus which examines optical characteristics of the articles against a viewing background.
U.S. Pat. No. 5,966,217 to Roe et al. discloses a system for analyzing articles wherein reflected radiation is split into a plurality of streams which are then filtered and analyzed.
Thus, it is seen that although there have been many arrangements proposed for the examination of a stream of articles by analysis of reflected and/or transmitted electromagnetic radiation from the articles, there is a continuing need for improved systems.
A system for sorting articles includes a feed conveyor for launching the articles across an airspace toward a first destination. A light source is provided for shining light energy on the articles in the airspace. A light collector is provided for collecting light energy reflected from the articles in the airspace. A deflector is provided for deflecting selected articles toward an alternative destination as the articles fly across the airspace. A control system is operably connected to the collector and the deflector for actuating the deflector in response to a sensed parameter (such as color) of the light energy collected in the collector.
The light source and collector are placed on one side of the air space and a calibration reflector is located on an opposite side of the airspace. The calibration reflector may be a retro-reflector constructed to reflect light back in a direction opposite and parallel to a direction at which the light falls upon the reflector. Such a reflector provides substantially total reflection of white light so that the sensor system can be calibrated whenever an article is not present in the airspace.
In another embodiment, the collector of the system includes an array of collector elements spaced across the width of the feed conveyor. Each collector element is connected to a light supply conduit which conducts the light energy to a multi-plexer. The multi-plexer receives light from each of the light supply conduits and then sequentially transfers the light from each light supply conduit to a common light transfer conduit. The common light transfer conduit conducts the light energy to a common analyzer unit for analyzing the light from all of the collector elements.
In another aspect of the invention, the multiplexer comprises a stator connected to each of the light supply conduits and connected to the common light transfer conduit. The multiplexer further includes a rotor carrying a light conducting tube for sequentially conducting light from each light supply conduit to the common light transfer conduit as the rotor rotates relative to the stator.
The present invention further includes methods of using the sorting system and its various components.
It is therefore a general object of the present invention to provide improved apparatus and methods for sorting objects by material and/or color, and particularly for sorting plastic bottles and the like.
Still another object of the present invention is the provision of a system for sorting objects wherein the objects are analyzed as they fly through an airspace, thus eliminating problems associated with analyzing objects lying on a supporting surface.
And another object of the present invention is the provision of a multiplexer for receiving multiple parallel streams of light energy and for sequentially conducting those multiple inlet streams to a common outlet stream.
And another object of the present invention is the provision of an improved reflector design for substantially completely reflecting white light energy incident thereon.
Other and further objects, features and advantages of the present invention will be readily apparent to those skilled in the art upon a reading of the following disclosure when taken in conjunction with the accompanying drawings.